The embodiments described herein relate to apparatus and methods for supporting the body weight of a patient. More particularly, the embodiments described herein relate to apparatus and methods for supporting the body weight of a patient during gait therapy.
Successfully delivering intensive yet safe gait therapy to individuals with significant walking deficits can present challenges to skilled therapists. In the acute stages of many neurological injuries such as stroke, spinal cord injury, traumatic brain injury, or the like individuals often exhibit highly unstable walking patterns and poor endurance, making it difficult to safely practice gait for both the patient and therapist. Because of this, rehabilitation centers often move over-ground gait training to a treadmill where body-weight support systems can help minimize falls while raising the intensity of the training.
Numerous studies have investigated the effectiveness of body-weight supported treadmill training and have found that this mode of gait training promotes gains in walking ability similar to or greater than conventional gait training. Unfortunately, there are few systems for transitioning patients from training on a treadmill to safe, weight-supported over-ground gait training. Furthermore, since a primary goal of most individuals with walking impairments is to walk in their homes and in their communities rather than on a treadmill, it is often desirable that therapeutic interventions targeting gait involve over-ground gait training (e.g., not on a treadmill).
Some known support systems involve training individuals with gait impairments over smooth, flat surfaces. In some systems, however, therapists may be significantly obstructed from interacting with the patient, particularly the lower legs of the patient. For patients that require partial assistance to stabilize their knees and/or hips or that need help to propel their legs, the systems present significant barriers between the patient and the therapist.
Some known gait support systems are configured to provide static unloading to a patient supported by the system. That is, under static unloading, the length of shoulder straps that support the patient are set to a fixed length such that the patient either bears substantially all of their weight when the straps are slack or substantially no weight when the straps are taught. Static unloading systems have been shown to result in abnormal ground reaction forces and altered muscle activation patterns in the lower extremities. In addition, static unloading systems may limit the vertical excursions of a patient that prevent certain forms of balance and postural therapy where a large range of motion is necessary. For example, in some known support systems, the extent of the vertical travel of the system is limited. As a result, some known systems may not be able to raise a patient from a wheelchair to a standing position, thereby restricting the use of the system to individuals who are not relegated to a wheelchair (e.g., those patients with minor to moderate gait impairments).
In some known static support systems, there may be a limitation on the amount of body-weight support. In such a system, the body-weight support cannot be modulated continuously, but rather is adjusted before the training session begins and remains substantially fixed at that level during training. Furthermore, the amount of unloading cannot be adjusted continuously since it requires the operator to manually adjust the system.
In other known systems, a patient may be supported by a passive trolley and rail system configured to support the patient while the patient physically drags the trolley along the overhead rail during gait therapy. While the trolley may have a relatively small mass, the patient may feel the presence of the mass. Accordingly, rather than being able to focus on balance, posture, and walking ability, the patient may have to compensate for the dynamics of the trolley. For example, on a smooth flat surface, if the subject stops abruptly, the trolley may continue to move forward and potentially destabilize the subject, thereby resulting in an abnormal compensatory gait strategy that could persist when the subject is removed from the device.
Some known over-ground gait support systems include a motorized trolley and rail system. In such known systems, the motorized trolley can be relatively bulky, thereby placing height restrictions on system. For example, in some known systems, there may be a maximum suitable height for effective support of a patient. In some known systems, a minimum ceiling height may be needed for the system to provide support for patients of varying height.
While the trolley is motorized and programmed to follow the subject's movement, the mechanics and overall system dynamics can result in significant delays in the response of the system such that the patient has the feeling that they are pulling a heavy, bulky trolley in order to move. Such system behavior may destabilize impaired patients during walking. Moreover, some known motorized systems include a large bundle of power cables and/or control cables to power and control the trolley. Such cable bundles present significant challenges in routing and management as well as reducing the travel of the trolley. For example, in some known systems, the cable bundle is arranged in a bellows configuration such that the cable bundle collapses as the trolley moves towards the power supply and expands as the trolley moves away from the power supply. In this manner, the travel of the trolley is limited by the space occupied by the collapsed cable bundle. In some instances, the bundle of cables can constitute a varying inertia which presents significant challenges in the performance of control systems and thus, reduces the efficacy of the overall motorized support system.
Thus, a need exists for improved apparatus and methods for supporting the body-weight of a patient during gate therapy.